Ultraviolet (UV) lights encompass lights having wavelengths of 4 to 400 nanometers. The longer wavelengths of the ultraviolet light spectrum are called black light, which have wavelengths slightly shorter than those that are normally visible and is generally safe for human viewing. Black light appears as a deep blue light because only a portion of the light has long enough wavelengths to be visible to human. For the purpose of this invention, blue black lights are simply called black light. An example of a shorter wavelength in the ultraviolet light spectrum is germicidal ultraviolet light that emits a much shorter wavelength that is dangerous to human skin and eyes.
The barely visible and invisible black light energizes fluorescent and/or phosphorescent pigments which then re-emits the light in visible colors. This results in the object appearing to have an independent glow as if internally lit. Black lights have been used as a source of illumination in theatrical productions, amusement park rides and home use for illuminating art covered with fluorescent and/or phosphorescent paint, and for general atmospheric effects for numerous years.
A black light source is generally a tube, similar to a fluorescent tube that produces white light, of a certain length and is not conveniently portable due to the size and the need of either alternating current or large voltage direct current. While black light has been used to illuminate all sorts of fluorescent or phosphorescent objects, black light as a portable device has not been used.
Using light emitting diodes (LEDs) that can produce UV black lights (generally known as UV LED), a portable black light device is provided. UV LEDs are similarly sized as typical prior art LEDs and can be powered by direct current such as batteries.
Therefore, there is a need for a portable black light device that can provide entertaining and promotional values.